Medical devices having full or partial polymer coatings and their methods of manufacture

ABSTRACT

Medical devices for insertion into the body of human or veterinary patients, wherein the device comprises a) a working element (e.g. a wire, a guidewire, a tube, a catheter, a cannula, a scope (e.g., rigid or flexible endoscope, laparoscope, sigmoidoscope, cystoscope, etc.) a probe, an apparatus for collecting information from a location within the body (e.g., an electrode, sensor, camera, scope, sample withdrawal apparatus, biopsy or tissue sampling device, etc.) which has an outer surface and b) a continuous or non-continuous coating on the outer surface of the working element. The outer surface of the working element is prepared to create a surface topography which promotes mechanical or frictional engagement of the coating to the working element. In some embodiments the coating is a lubricious coating, such as a fluorocarbon coating or a hydrogel that becomes lubricious when contacted by a liquid. In some embodiments, the coating may expand as swell. Also disclosed as methods for manufacturing such devices.

RELATED INVENTION

This patent application claims priority to pending U.S. application Ser.No. 10/177,651 filed on Jun. 20, 2002 and U.S. Provisional PatentApplication Ser. No. 60/299,645 filed on Jun. 20, 2001, which isexpressly incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to biomedical devices andmethods for manufacturing biomedical devices and more particularly tobiomedical devices that have full or partial polymer coatings and theirmethods of manufacture.

BACKGROUND OF THE INVENTION

Medical instruments are frequently coated with various polymers toreduce sliding friction (e.g. by lubricity) and provide otherperformance enhancing characteristics. Obtaining adequate adherence ofthe polymer coating to the instrument substrate is a problem in manyinstances and particularly when a hydrogel is coated on a metalsubstrate.

Various hydrophylic and hydrophobic polymer coatings and their methodsof application have been described in U.S. Pat. Nos. 4,263,372 Method ofcoating and/or impregnating porous substrates, and products obtainedthereby (Emmons et al.); 4,435,476 Method of making an abrasionresistant coating on a solid substrate and articles produced thereby(Phillips et al.); 4,504,528 Process for coating aqueous fluoropolymercoating on porous substrate (Zuckeret al.); 4,541,980 Methods ofproducing plastic-coated metallic members (Kiersarsky et al.); 4,705,584Application of polymeric materials to substrates (Lauchenauer);4,729,914 Hydrophilic coating and substrate coated therewith (Kliment etal.); 4,784,159 Process for making an implantable device having a plasmasprayed metallic porous surface (Szilagyi); 5,095,915 Guidewire withflexible distal tip (Engelson); 5,129,890 Hydrophilically coatedflexible wire guide (Bates et al.); 5,235,964 Flexible probe apparatus(Abenaim); 5,290,585 Lubricious hydrogel coatings (Elton); 3,969,552Process for impregnating porous articles (Malofsky et al.); 4,147,821Impregnation of porous articles (Young); 4,556,701 Impregnatecompositions for porous substrates (Schindler et al.); 5,333,620 Highperformance plastic coated medical guidewire (Moutafis et al.);5,441,488 Medical tool having lubricious surface in a wetted state andmethod for production thereof (Shimura et al.); 5,443,455 Guidewire andmethod of pretreating metal surfaces for subsequent polymer coating(Hergenrother et al.); 5,443,907 Coating for medical insertion guides(Slaikeu et al.); 5,437,288 Flexible catheter guidewire (Schwartz etal.); 5,573,520 Flexible tubular device for use in medical applications(Schwartz et al.); 5,749,968 Device for priming for improved adherenceof gels to substrates (Melanson et al.); 5,750,206 Method of pretreatingmetal surfaces for subsequent polymer coating (Hergenrother et al.);5,833,632 Hollow guide wire apparatus catheters (Jacobsen et al.);5,700,559 Durable Hydrophilic Surface Coatings (Sheu et al.); 6,080,488Process for preparation of slippery, tenaciously adhering, hydrophilicpolyurethane hydrogel coating . . . medical devices (Hostettler et al.);6,149,978 Coating of porous, hydrophobic substrates with thermoplasticfluoropolymers (Bladel et al.); 6,162,310 Method for producing poroussponge like metal (Tseng); 6,176,849 Hydrophilic lubricity coating formedical devices comprising a hydrophobic top coat (Yang et al.);5,840,046 Guidewire Having Hydrophilic Coating (Deem); 5,984,878(Multi-Coating Stainless Steel Guidewire (Engelson) as well as PCTInternational Patent Publications WO 92/11877 Biocompatible abrasionresistant coated substrates (Fan et al.) and WO 00/65143 Process forcoating a perforated substrate (Munro et al.), all of which areexpressly incorporated herein by reference.

One reason for applying polymer coatings to insertable medical devicesis to impart lubricity to, or to lower the coefficient of friction of,the outer surface of the device. Some of these polymer coatings, such asfluorocarbon coatings (e.g., polytetrafluoroethylene) provide alubricious hydrophobic surface while others such as swellable hydrogelsare hydrophilic and become lubricious after coming in contact withliquid (e.g., blood or other body fluid).

For example, U.S. Pat. No. 5,573,520 (Schwartz et al.) describes aflexible tubular member encased by a fluid tight polymer covering,including a hydrogel, for use as a guidewire, catheter or introducer.However, the polymer covering is only described as covering either theinside surface or the outside surface for the purposes of a fluid tightsealing of apertures or for providing lubricity. As described earlier,these benefits of coatings are known in the art. However, Schwartz etal. does not describe the coating to be integral to the wall of thedevice or there being any sort of interlock or other improved attachmentof the coating.

Also, U.S. Pat. No. No. 5,840,046 (Deem) describes guidewires havinghydrophilic coatings, such as hydrophilic polysaccharides (e.g.,hyaluronic acid or chondroitin sulfate). The guidewires are made of wirewhich is helically coiled about a core member. The spacing betweenadjacent coils of the wire is wide enough to allow the coating to flexalong with the coil but narrow enough to prevent the coating frompenetrating into an annular space that exists between the coiled wireand the inner core member.

SUMMARY OF THE INVENTION

The present invention provides novel polymer coated medical instrumentsincluding guidewires, catheters, cannula, endoscopes and otherinstruments for insertion into the body.

In accordance with the present invention, there are provided medicaldevices that are insertable into the bodies of human or veterinarypatients, each such device comprising a) a working element having anouter surface and b) a polymer coating disposed on at least a portion ofthe outer surface of the working element, wherein the outer surface ofthe working element has a topography characterized by surface featureswhich deter longitudinal slippage of the coating over the outer surfaceand or which result in some mechanical engagement or interlock betweencoating and the working element. In this regard, the outer surface ofthe working element may have one or more cavities formed therein, atleast some of those cavities having side walls which are disposed atangles of about 75 or more degrees relative to the longitudinal axis ofthe working element (or relative to the outer surface of the workingelement immediately adjacent to those side walls) and wherein at least aportion of the polymer coating extends into at least some of thecavities so as to deter separation of the polymer coating from theworking element. In this manner the present invention may provide analternative to the use of adhesive coatings or chemical adhesive layerssuch as the “tie layers” described in U.S. Pat. No. 5,749,837 (Palermo),which is expressly incorporated herein by reference.

Further in accordance with the invention, the cavities formed in theouter surface of the working element may comprise holes, grooves, acontinuous helical or curved groove, slots, pores, apertures or otherexternal surface features to provide a substantial improvement in theadherence of a polymer coating. The coating fills into at least some ofthe cavities to form a mechanical bond or interlock with the workingelement. To accomplish such mechanical bond or interlock, the cavitiesare preferably at least about 0.001 inch deep and may extend completelythrough the working element forming a through-hole or slot. In at leastsome embodiments, it is preferable that the polymer coating to penetrateto a depth below the outer surface that is at least about 25%, and morepreferably at least about 50%, of the total thickness of the polymercoating on that portion of the device. Thus, for example, in a regionwhere the polymer coating is a total of 100 mills thick, it will bepreferable for the coating to penetrate into cavities at least about 25mills below the outer surface and more preferably at about 50 millsbelow the outer surface. The coating need not be for the purpose ofproviding lubricity, although such is one purpose for the invention.Indeed, the coating may serve any purpose, such as the creating of abiocompatible barrier to insulate the patients body from toxic,infectious or non-biocompatible materials on the underlying surface ofor within the device.

Still further in accordance with the invention the working element maycomprise any apparatus or device that is insertable into the body,including but not limited to a wire, a guidewire, a tube, a catheter, acannula, a scope (e.g., rigid or flexible endoscope, laparoscope,sigmoidoscope, cystoscope, etc.) a probe, an apparatus for collectinginformation from a location within the body (e.g., an electrode, sensor,camera, scope, sample withdrawal apparatus, biopsy or tissue samplingdevice, etc.). The working element's outer surface may be made from aradiopaque, biocompatible metal such as platinum, gold, tungsten,nitinol, elgiloy, stainless steel, or tantalum but may be made of apolymer impregnated or otherwise modified to be visible under x-rays byvarious means known in the art. Alternatively, the working element'souter surface may be made of a plastic or polymer material which, in atleast some embodiments, may be visualized under ultrasound, magneticresonance imaging, radiographic imaging or other medical visualizationmethods known in the art.

Still further in accordance with the present invention, the polymercoating may comprise a material that is lubricious or has a lowcoefficient of friction, such as polytetrafluoroethylene (e.g. Teflon).Also, the polymer coating may comprise a hydrophilic polymer (i.e.hydrogel) that creates a lubricious surface after being exposed to aliquid (e.g., blood or other body fluid). It is preferable that thehydrogel be polymerized from ethylenically unsaturated monomers. In somecases, environmentally responsive hydrogels may be used such as thatdescribed in cozening U.S. patent application Ser. No. 09/804,935entitled Hydrogels That undergo Volumetric Expansion In Response ToChanges In Their Environment And Their Methods Of manufacture And Use.Specific examples of hydrogels that may be used include those describedin U.S. Pat. Nos. 4,729,914 (Kliment), 5,290,585 (Eiton), 5,331,027(Whitboume), 6,080,488 (Hostettlerel al.), 6,176,849 (Yang et al.) andpending U.S. patent application Ser. No. 09/804,935 entitled HydrogelsThat undergo Volumetric Expansion In Response To Changes In TheirEnvironment And Their Methods Of manufacture And Use, each of which isexpressly incorporated herein by reference. In some embodiments of theinvention, the polymer may be formed about the outer surface of theworking element in a non-continuous manner (e.g., in discrete ridges,bumps or areas) or such polymer coating may be disposed in a manner thatforms a generally smooth continuous polymer coating surface. In someembodiments, the polymer coating may be radioopaque.

Even further aspects of this invention will be come apparent to those ofskill in the art upon reading of the detailed description of exemplaryembodiments set forth herebelow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a guidewire which has a polymer coatingdisposed thereon in accordance with the present invention.

FIG. 2 is an enlarges, cut-away view of portion 2 of the guidewire ofFIG. 1.

FIG. 3 is an enlarged view of portion 3 of FIG. 2.

FIG. 4 is an enlarged view of portion 4 of FIG. 3.

FIG. 5 is a partial longitudinal sectional view of another guidewirewhich has a polymer coating disposed thereon in accordance with thepresent invention.

FIG. 6 is a partial longitudinal sectional view of a solid, elongateprobe which has a polymer coating disposed thereon in accordance withthe present invention.

FIG. 7 is a partial longitudinal sectional view of an elongate tubulardevice such as a catheter, scope, cannula, introducer, sheath, or thelike having a polymer coating disposed thereon in accordance with thepresent invention.

FIG. 8 is a partial longitudinal sectional view of an elongate devicehaving another polymer coating disposed thereon in accordance with thepresent invention.

FIGS. 9 a-9 d show, in step by step fashion, a method for manufacturinga device having a polymer coating disposed thereon in the manner shownin FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

The invention is described herebelow with reference to certain examplesor embodiments as shown in the accompanying drawings. These examples orembodiments are not limiting, but rather are merely exemplary of some ofthe ways in which the present invention may be reduced to practice.

FIGS. 1-4 show an example of a guidewire 10 that bears a polymer coatingaccording to this invention. As shown, the guidewire 10 comprises anelongate, flexible body 12 having a blunt distal tip member 18positioned at its distal end. The guidewire body 12 comprises acontinuous, tightly wound, helical coil formed of wire 14. A solid ortubular core member 16 may optionally be disposed within the helicallywound wire 14. Pores 22 are formed in at least the outer surface of thehelically coiled wire 14. A polymer coating 20 is disposed on the outersurface of the guidewire body 12, as shown. A portion of such polymercoating extends into some of the pores 22 at the surface of the wire 14,as can be appreciated from the showing of FIG. 4. The wire 14 is made ofa porous material or is treated to have a porous surface. If a porousmaterial is used, secondary cutting or surface treatment of the wire 14may be avoided or reduced. Microporous metal can be fabricated bysintering process, plasma spraying (see U.S. Pat. No. 4,784,159) orother means known in the art. One biologically compatible, porous,sintered metal is commercially available from Implex Corp., Allendale,N.J. under the tradename Hedrocel.® In the device shown in FIGS. 1-4,the coating 20 has impregnated the pores 22 of the wire 14 to form amechanical bond. One example of an acceptable coating is a fluoropolymercoating and applied by the methods described by Bladel et al. in theU.S. Pat. No. 6,149,978. Another example is an acceptable coating is aswellable hydrogel. Optionally, the coating may be modified, impregnatedor otherwise combined with a variety of pharmacologic or bioactivesubstances (e.g. chemicals, drugs, proteins, peptides, or growthfactors) to impart anti-infective, anti-thrombogenic or other desirableinteractions with the body.

Although the example shown in FIGS. 1-4 is a guidewire 10, it is to beappreciated that the working element on which the coating 20 is appliedmay comprise any insertable medical device, including but not limited toa catheter, cannula, probe, scope, electrode, other wire, sensor, etc.

As shown in FIGS. 2 and 4, it will be further appreciated that, in atleast some embodiments of the invention (e.g., guidewires, scopes,catheters, other elongate devices that are insertable and retractableinto and out of the body), the medical device will have a longitudinalaxis LA along which the device is typically advanced and retracted. Awall axis WA projected parallel to a portion of a wall of a cavity 20(e.g., slot, pore, groove, aperture or other opening or depression)within which the polymer is deposited may be perpendicular, nearlyperpendicular or non-parallel to the longitudinal axis, as shown.Preferably, the angle A between the longitudinal axis LA and wall axisWA will be at least 75 degrees and preferably at least 90 degrees. Incases where the angle A is greater than 90 degrees, an undercut will becreated and such undercut will create a firm mechanical interlockbetween the coating 20 and the surface of the working element (e.g., thebody 12 of the guidewire, catheter, scope, probe, wire, electrode,sensor, etc.). In these embodiments, any slippage or separation of thepolymer coating 20 from the device 10 would require the polymer coating20 to move outwardly along the wall axis WA in order for the coating 20to pull out of the cavities 22 into which it is deposited. Since thiswall axis WA is non-parallel to the longitudinal axis of the device,routine advancement and retraction of the device along its longitudinalaxis will not facilitate unwanted slippage or movement of the polymer inthe direction of the wall axis and the penetration or extension of thecoating 20 into the cavities 22 will reduce the potential for unwantedlongitudinal slippage or separation of the polymer coating 20 from thedevice 10 as the device 10 is routinely advanced into and retracted fromthe patient's body.

Variations of the working element and/or variations in the types ofcavities formed in its surface are shown in FIGS. 5-8. Specifically,FIG. 5 shows a section of another guidewire 30 which comprises ahelically would coil of relatively non-porous steel wire 32 having apolymer coating 34 disposed on the outer surface 38 thereof. An optionaltubular core member 36 is positioned within the coiled wire 32. Theouter surface 38 of the wire 32 has been treated by a mechanicalabrasion process or chemical etching by an acid or other chemical whichresults in microtexturing of the outer surface, as shown. Thismicrotextured outer surface 38 has cavities 39 (e.g., indentations,pits, depressions, grooves, a single helical or curved groove, etc.)formed therein. The coating 34 has entered some or all of the cavities39, thereby creating a mechanical interlock between the outer surface 38of the device 30 and the coating 34.

FIG. 6 shows a substantially solid member 42, such as a probe or scope,which has generally rectangular cavities in the nature of slots 46formed inwardly from the outer surface 47 thereof. A polymer coating 44is disposed continuously over the outer surface 47 of the solid member42. A longitudinal axis LA is projectable through the solid member 42. Awall axis WA is projectable along the side wall 48 of each slot 46. Forat least some of the slots 46, the wall axis WA is substantiallyperpendicular to the longitudinal axis LA, such that angle A will beapproximately 90 degrees, as shown in FIG. 6. It will be appreciatedthat, in some embodiments, the side walls 48 of at least some slots 46may be slanted or angled such that the slot 46 is wider at its bottom Bthan at its top T, thereby creating an undercut which furthermechanically locks or frictionally engages the coating 44 to the solidmember 42.

FIG. 7 shows yet another example of the present invention. In theexample of FIG. 7, the working element of the device comprises a tubularcatheter or cannula 50. A metal tube 53 which has slots or holes 58formed therein is used as a backbone for the catheter or cannula 50. Amandrel or other space occupying member (not shown) is placed within thearea of the lumen 56 and a polymer coating 54 is applied such that thepolymer coating 54 permeates though the slots 58 and into contact withthe mandrel or other space occupying member. After the coating hassolidified, the mandrel or other space occupying member is removed tocreate the lumen 56. The polymer coating 54 thus creates a continuoussidewall of the tubular catheter or cannula 50 with the slotted metaltube 52 forming a backbone, skeleton or scaffold for the polymercoating.

FIG. 8 shows yet another example of the present invention. In theexample of FIG. 8, the working element of the device 60 comprises atubular catheter body 62 formed of a plastic material and having a lumen66 extending longitudinally therethrough. Cavities 68, in the nature ofblind bore holes, slots or groves, extend downwardly from the outersurface 69 of the catheter body 62 but do not penetrate into the lumen66. Quantities of coating 64 are deposited in each cavity 62 andprotrude upwardly above the outer surface of the catheter 69. Thequantities of coating 64 may be discreet and unconnected to one another,as shown in FIG. 8, to thereby form a non-continuous coating comprisinga system of rased knobs, bumps, ridges, etc. The coating 64 may bedeposited into the cavities 68 so that a meniscus or heap of coating 64protrudes out of the top of each cavity 68. Alternatively, the coating64 may be a swellable or expandable coating such as a hydrophilicmaterial (e.g., a hydrogel) and such coating 64 may be initiallydeposited within each cavity 62 such that the top surface of the coating64 is flush with or below the adjacent outer surface 69 of the catheterbody 62 and such coating 64 may subsequently swell of expand such thatit will protrude upwardly above the adjacent outer surface 69, asdesired. Such selling or expansion may, in some embodiments, occur whenthe coating 64 is in contact with a liquid or body fluid for sufficienttime to cause the desired swelling or expansion of the coating 64.

FIGS. 9 a-9 d show, in step by step fashion, a method for manufacturinga device having non-continuous, discrete deposits of a polymer coating,such as the device 60 of FIG. 8. In this method, a working element suchas a wire, a guidewire, a tube, a catheter, a cannula, a scope (e.g.,rigid or flexible endoscope, laparoscope, sigmoidoscope, cystoscope,etc.) a probe, an apparatus for collecting information from a locationwithin the body (e.g., an electrode, sensor, camera, scope, samplewithdrawal apparatus, biopsy or tissue sampling device, etc.) formed ofany suitable material such as metal or plastic is initially provided asshown in FIG. 9a. A plurality of cavities 66 such as blind bore holes,slots, indentations, depressions, cuts, grooves, etc. are formed in theouter surface 62 of the working element 62. This may be accomplished byany technique known in the art such as mechanical drilling, boring,laser etching, cutting, EDM, photochemical etching, etc. As shown inFIG. 9 b, wall axes WA projected parallel to at least portions of thesidewalls 65 of at least some of the cavities 66 preferably form anangle A relative to the longitudinal axis LA of the working element or alongitudinal axis of the working element's outer surface 63 arepreferably greater than 75 degrees and more preferably greater than 90degrees. In some embodiments, as shown in FIG. 9 b (alt) the sidewalls65 a of the cavities 66 a may be angled or curved such that the cavities66 a are wider at their bases B than at their tops T. This results inthe formation of an angle A greater than 90 degrees and forms anundercut whereby the later-applied coating 64 (FIGS. 9 c-9 d) becomesmechanically or frictionally interlocked or engaged by the sidewalls 65a of the cavities 66 a.

After the cavities 66 or 66 a have been formed in the working element65, polymer coating 64 is deposited in the cavities 66 or 66 a. In someembodiments, such as the specific example shown in FIGS. 9 c-9 d, thecoating 64 is a swellable or expandable coating 64 which swells orexpands after coming in contact with a body fluid BF such as blood orother liquid such as saline solution or sterile water. The coating 64may be initially applied over the entire outer surface 66 of the workingelement 62 and the layer of coating deposited on the outer surface maythen be wiped or scraped away, or otherwise removed, leaving discretedeposits of coating 64 within the cavities 66 such that the uppersurface 64 us of each mass of coating 64 is substantially flush with oreven slightly below the level of the outer surface 66.

Thereafter, when the working element 62 is immersed in blood or otherbody fluid BF or when it is immersed in of contacted by a liquid(saline, water, etc.), the deposits of polymer coating 64 will expand orswells such that the upper surface US of each coating deposit 64protrudes above the outer surface 66 of the working element 62.Alternatively, the polymer coating may expand in response to changes inits environment, such as changes in pH. In this manner, the expansion ofthe polymer coating creates a non-continuous coating system whichcomprises discrete raised knobs, bumps, ridges, etc. of polymer coating64, on the outer surface 66 of the working element 62. Such coating 64may impart lubricity or form a slippery substance which facilitates thedesired insertion, positioning, movement and/or withdrawal of theworking element 62 from the body of a human or veterinary patient.

The invention has been described herein with reference to certainexamples and embodiments only. No effort has been made to exhaustivelydescribe all possible examples and embodiments of the invention. Indeed,those of skill in the art will appreciate that various additions,deletions, modifications and other changes may be made to theabove-described examples and embodiments, without departing from theintended spirit and scope of the invention as recited in the followingclaims. For example, the particular elements and attributes of anyparticular embodiment or example may be combined with or substituted forelements or attributes of any other embodiment wherever such addition orsubstitution does not render the resultant device unuseable orunsuitable for its intended application. Also, although specific typesof coating have been referred to herein, many other types of lubricious,non-lubricious, hydrophilic and/or hydrophobic coatings may be used indevices of this invention. Accordingly, it is intended that all suchadditions, deletions, modifications and other changes be included withinthe scope of the following claims.

1. A medical device that is insertable into the body of a human orveterinary patient, said device comprising: a working element having anouter surface; a polymer coating disposed on at least a portion of theouter surface of the working element; the outer surface of said workingelement having cavities formed therein, at least some of said cavitieshaving side walls which are disposed at angles of about 75 or moredegrees relative to the outer surface of the working element immediatelyadjacent to side walls; and, at least a portion of said polymer coatingextending into said cavities so as to deter separation of the polymercoating from the working element.
 2. A device according to claim 1wherein the working element comprises a catheter or cannula.
 3. A deviceaccording to claim 1 wherein the working element comprises a guidewire.4. A device according to claim 1 wherein the working element comprises ascope.
 5. A device according to claim 1 wherein the working elementcomprises an apparatus for obtaining information from a location withinthe patient's body.
 6. A device according to claim 1 wherein the polymercoating is lubricious.
 7. A device according to claim 1 wherein thepolymer coating becomes lubricious upon contact with a liquid.
 8. Adevice according to claim 1 wherein the polymer coating comprises ahydrogel.
 9. A device according to claim 1 wherein the polymer coatingcomprises a porous hydrogel.
 10. A device according to claim 1 whereinthe polymer coating expands in the presence of liquid.
 11. A deviceaccording to claim 1 wherein the cavities formed in the outer surface ofthe working element comprise pores.
 12. A device according to claim 1wherein the cavities formed in the outer surface of the working elementcomprise grooves.
 13. A device according to claim 1 wherein the cavitiesformed in the outer surface of the working element comprise depressions.14. A device according to claim 1 wherein the cavities formed in theouter surface of the working element comprise indentations.
 15. A deviceaccording to claim 1 wherein the cavities formed in the outer surface ofthe working element comprise holes.
 16. A device according to claim 1wherein the cavities formed in the outer surface of the working elementcomprise slots.
 17. A device according to claim 1 wherein the cavitiesformed in the outer surface of the working element extend only partiallyinto the working element.
 18. A device according to claim 1 wherein thecavities formed in the outer surface of the working element extendthrough the working element.
 19. A device according to claim 1 whereinthe porosity of the polymer coating is at least about 50%.
 20. A deviceaccording to claim 1 wherein the polymer coating extends into cavitiesat least 0.001 inch below the outer surface.
 21. A device according toclaim 1 wherein the polymer coating extends into cavities such that thepolymer coating extends to a depth below the outer surface that is atleast about 25% of the total thickness of the polymer coating at thatlocation.
 22. A device according to claim 21 wherein the porosity of thepolymer coating, when substantially fully expanded, is between about 50%and about 95%.
 23. A device according to claim 1 wherein substantiallyall of the polymer coating is initially contained within the cavitiesand such polymer coating subsequently expands such that a portion ofsaid polymer coating protrudes out of the cavities.
 24. A deviceaccording to claim 1 wherein substantially all of the polymer coating isinitially contained within the cavities beneath the outer surface andsuch polymer coating subsequently expands such that a portion of saidpolymer coating protrudes out of the cavities and above the outersurface.
 25. A device according to claim 1 wherein the polymer coatingcomprises a fluorocarbon.
 26. A device according to claim 1 wherein thepolymer coating comprises polytetrafluoroethylene.
 27. A deviceaccording to claim 1 wherein the angle is at least 90 degrees. 28 Adevice according to claim 1 wherein the angle is greater than 90 degreesthereby creating an undercut surface.
 29. A device according to claim 1wherein the polymer coating expands when in contact with a liquid.
 30. Adevice according to claim 1 wherein the polymer coating comprises ahydrogel that expands when in contact with a liquid.
 31. A method formanufacturing a coated medical device which comprises a working parthaving an outer surface and a longitudinal axis, said working part beinginsertable into the body of a human or veterinary patient, said methodcomprising the steps of: (A) treating at least a portion of the outersurface to create a surface topography which includes cavities; and, (B)applying a polymer coating to the outer surface such that the surfacetopography deters separation of the coating from the outer surface. 32.A method according to claim 31 wherein Step A comprises forming cavitiesat least 0.001 inch into the outer surface.
 33. A method according toclaim 31 wherein Step A comprises forming a continuous depression in theouter surface.
 34. A method according to claim 33 wherein the continuousdepression comprises a helical groove.
 35. A method according to claim32 wherein Step A comprises forming undercut cavities in the outersurface.
 36. A method according to claim 31 wherein Step B comprisesapplying a lubricious coating.
 37. A method according to claim 31wherein Step B comprises applying a non-lubricious coating.
 38. A methodaccording to claim 31 wherein Step B comprises applying an expandablecoating.
 39. A method according to claim 38 wherein Step B comprisesapplying a coating that expands when in contact with a liquid.
 40. Amethod according to claim 31 wherein Step B comprises applying a coatingthat expands in response to a change in its environment.
 41. A methodaccording to claim 40 wherein Step B comprises applying a coating thatexpands in response to a change in the pH of its environment.
 42. Amethod according to claim 31 wherein Step A comprises creating cavitiesin the outer surface.
 43. A method according to claim 41 wherein Step Bcomprises applying the polymer coating such that the coating extendsinto cavities to a depth below the outer surface that is at least about25% of the total thickness of the polymer coating at that location onthe device.
 44. A method according to claim 31 wherein Step B comprisesapplying the polymer coating such that the polymer coating extends to adepth of at least 0.001 inch below the plane of the outer surface.